Process of refining magnesium and its alloys



Patented July 9, 192 9.

GUSTAV PISTOR, 0F LEIPZIG, GERMANY, A SSIGNOR TO I. G. FARBENINDUSTRIEnxi'rnnensntnscmr, or FnANxnom-on-TnE-nmmGERMANY, A CORPORA- TION 0FGERMANY;

:enocnss or nnrmme naennsmm AND ITS ALLOYS.

The present invention relates to a process of refining magnesium andalloyscontaming at least 85% of magnesium, the remain der being aluminumor zinc or both.

1,576,080 processes are. described according to which magnesium and itsalloys are refined by melting the raw metal witha small amount'ofmagnesium chloride or of a mixture of magnesium chloride and athickening medium such as magnesia, calcium fluoride etc.

Now I have found that improved results are obtained when during theabove mentioned process metallic calcium and.n1an ganese is introducedinto the molten metal. The metallic calcium combined with man ganeseexercises a refining action which cannot be attained to the same extentwhen em-' ploying either magnesium chloride or mag' nesiumchloride withthe addition of a thickening medium. It surpasses furthermore therefining action of mixture of magnesium chloride and a thickening mediumwith the addition of either calcium or manganese.

I have also found that this process shall be carried out in such amanner that as the final product an alloy is obtained containing acertain percentage of calcium and manganese. I have found that thealloys containing from 0.01 to 0.1% calcium and, from 0.1 to 0.4%manganese the remainder being magnesium or a magnesium alloy of at leastabout 85% magnesium, possess highly anticorrosive properties.

To perform my process I proceed as described in the following example.In the first stage, metallic calcium is introduced at about 700 G. into'the molten metal covered with the thickened melt of salts as describedin the cited specification so as to attain a concentration of about 0.5%of calcium metal in the molten metal. Hereupon the metal is thoroughlywashed with the salt melt by intense stirring until the main quantity ofthe 'calcium metal is removed from the metal, which may be ascertainedby observing the surface of the molten metaL' Thereupon, the salt layerhaving disappeared from the surface, its specific weight havingsurpassed that of the metal by taking up the impurities, a fresh amountof the salt melt is added contain- No Drawing. Application filedNovember 8, 1927, Serial No- 231,996, andin Germany November 13, 1926.

ing anhydrous manganous chloride in quantity theoretically suflicient toform an alloy with 1% and the melt. is stirred'anew v whlle heating upto temperatures of about In the U. S. Patent Nos. 1,524,470 and 900 C.toreduce part of the added manganous chloride to metal and to alloy thelatter with the magnesium. It is important to continue this operationuntil the continuously decreasing percentage of calcium amounts from0.01% to 0.1% at most, and the increasing percentage of manganese hasattained a maximum of 0.4%, a percentage of 0.1 generally beingsuflicienta After the stirring is finished a last portion of the saltmelt is placed upon the surface of the metal. During. the succeedingcooling, the regulus and the stirred and mixed salt melt will separateso that after attaining the best casting temperature, ascertained byexperiment, the pure metal can be cast. casting-. tempe1'ature dependsupon the composition of the alloy employed and is a different one formagnesium-zinc, magnesimnaluminum, magnesium-zinc-aluminum &c.

If desired the method may be modified by adding calcium and manganesesimultaneously, for instance, in the form of an alloy of calicum withmanganese, and then keeping the temperature at a higher level from thebeginning. Also instead of introducing the manganese in the nascentstate (using manganous chloride or other compounds capable of beingreduced by magnesium), the metal may be introduced in the form ofmetallic manganese, or of appropriate alloys rich in manganese, theother component of WhICh lS also a desirable constituent of themagnesium alloy, but this process of operating requires specialprecaution and experience, owing to the limited alloyability f manganeseand to the highertemperatur s which consequently are to be employed.

The

.Although the reactions taking place in connection with the presentprocess of refining raw magnesium or raw magnesium alloys are notcompletely clear in all details, it is quite sure that calcium as wellas man ganese exercise a refining action which cannot be attained to thesame extent by employing either of both metals alone. The simultaneouscontent of 0.1% Ca' at most and up to 0.4% Mn is not only innoxious,

but rather desirable for the benefit of attaining the above-mentionedimproved anticorrosive properties of the metal produced according to thepresent invention.

I claim:

1. The process of refining magnesium and tinuing the treatment until therefined metal contains 0.1% of calcium at most and up to 0.4% ofmanganese.

2. The process of refining magnesium and its alloys containing at least85% Mg which comprises stirring the molten metal with magnesium chlorideand a substance capable of actin as a thickening medium on magnesiumcoride, introducing into the molten metal calcium metal and a manganesecompound capable of being reduced by magnesium, and continuing thetreatment until the refined metal contains 0.1% of calcium at most andup to 0.4% of manganese.

3. The process of refining magnesium and its alloys containing at least85% Mg which comprises stirring the molten metal with magnesium chlorideand a substance adapted to act'as a thickening medium on magnesiumchloride, introducing inlo the molten metal calcium metal and manganouschloride, and continuing the treatment until the refined metal contains0.1% of calcium at most and up to 0.4% of manganese 4. A new alloy ofmagnesium containing from 0.01 to 0.1% calcium and from 0.1 to 0.4%manganese, the remainder being an alloy of at least 85% magnesium.

In testimony whereof I have hereunto set m hand.

y GUSTAV PISTOR.

